System of ship propulsion.



W. I.. R. EMMET. SYSTEM OF SHIP PROPULSION. I APPLICATION FILED SEPT. I7, I912. 1,137,593 7 Patented Apr. 27, 1915.

2 SHEETS-SHEET I.

In verwtow- William L.R.Ernmet,

HisJQLILQT-ne W. L. R. EMMET.

SYSTEM OF SHIP PROPULSION.

4 APPLICATION FILED $EPT.17, 1912. I 1 ,137,593. Patented Apr. 27, 1915 2 SHEETS-SHEET 2- Withesses:

Inventor: William L.R.Elmmet Jitter-115;.

His

; WILLIAM L.

a" nmnn'r, or iscnnnnczrnnr, nnw You, nssrenon To GENERAL nnncmnlc comm, A conrona'rzon or nnwxonx.

flpediflcetien of Letters refine: I PfitntedAph 27,1915.

Application and September 17, 1912.. Serial 1%. 729,33.

To all whom it may concern: 7

Be it known that I,'WILL'IA L. R. E Mm1', a citizen of theUnited States, residing at Schenectady, county of Schenectady, State of New York, have invented certain new and useful Improvements in Systems of Propulsion, of whfijchthe following 'is' a specification.

My invention relates to systems of ship' propulsion in which'the propeller shafts are rotated by electric motors receiving current uid turbines. f

The objects of my invention are to provide in a ship propulsion system of the type above described a novel combination and arrangement of apparatus for obtaining a more satisfactory and eflicient speed control than has heretofore been possible in a system of this character.

In propelling ships, particularly those of larger size, by electric m0tors,-'it is desirable to use alternating currents since the motors and generators for alternating currents are simpler than those for direct currents, the

generators canibe conveniently designed for larger capacities and higher speeds, and

therefore are better'adapted fir use with steam turbines. Alternating'c rrent motors of the simplest type require 'no commutators and can be constructed and wound in such a manner that they will stand the. roughest usage-with a minimum of trouble and ex pense' for maintenance. Such alternating f current motors,-however,"'arebestadapted to operation at speeds synchronous or nearly, synchronous with the speed of the .gener ator, and therefore'where such motors are used it is desirable to change the speed of the vessel by changing'the speed of'the genf erator'. When a steam turbine is used as the f prime mover of such a system, the 'speed' ofthe generator and 'motor can be varied by i simply changing the steam admission to the turbine, the resistance .of'the propeller balancing the force of the steam-and; the elec-' trical' apparatus "establishing a fixed ratio between the turbine speed and that of the propeller. Such method of'control would be adequate for handling a. vessel, were it [notfor the fact that it. is desirable to interriipt the electric circuit forpurposes of changing connections for reversing or for changing the arrangements. of, windings to give different ratios of speed reduction. In the.

event of such interruptions the load is removed the prime mover and it will im-' mediately acquire an excessive'speed' unless a means is provided for limiting it. Previous to my present-invention, such speed in-' crease of a' generator has been limited by an emergency trip which. served to shut ofi the steam entirely "when some predetermined speed of the generator had been reached. Such an arrangement is objectionable, since it cuts ofi' entirely the supply of steam to the turbine, and consequently the latter must be started anew when it is de- 1 sired to close the electric circuit.

peller driving motors.

I further provide a speed responsive device'which is adapted to shut off the supply of elastic fluid to the turbine when the turbine speed exceeds a certain predetermined limit, which limit is slightly inexcess of the maximum speed employed in operating the vessel. ThlS device does not, however,- shut off the elastic fluidv by tripping an emergency valve, but on the other hand it causes an admission valve, located preferably inthe main supply pipe, to close in such a manner that it will immediately and automatically .open againas soon as the turbine speed has fa'llen below the predetermined limit. With this arrangement, if the load is suddenly removed from the system, as

when the electriccircuit of the motors is interrupted, the turbine speed will'rise to the above, mentioned, and the latter :ad-

mission-valve will; automatically close to an extent 'suflicie'nt to prevent excessive speed. At this point, the turbine will operate withoutload, and at such a speed that it is ready for doing .work whenever the electric' circuits are closed agam. j

In the preferred embodiment of my inlatter.

vention, I employ, as described above, two separate systems of valves. One system of valves is controlled by hand and limits the quantity of elastic fluid admitted to the turbine, thereby controlling the speed of the The other valve system consists preferably of a throttle valve located in the main supply pipe. This valve is controlled by a speed-responsive device connected to the shaft of the turbine and operates merely to limit the maximum speed at which the turbine will run. The same result can obviously be accomplished by the use of the same system of valves for hand control of the turbine speed and for limiting the maximum turbine speed. In the latter event the speed-responsive device is so arranged that it cannot open the system of valves beyond the point fixed by the hand-control mechanism, but is free to close such valves if the maxiinum speed limit is exceeded, no matter what position the hand-control mechanism occupies.

The novel features which I believe to be characteristic of my invention will be definitely indicated in the claims appended hereto. The features of construction and mode of operation will be understood by reference to the following description taken in connection with the accompanying drawings which show the preferred embodiments of my invention, and in which Figure 1 is a diagrammatic view of a ship propulsion system involving the novel features of my invention, and Fig. 2 is an end elevation of the turbine of such a system, showing the hand-operated valves and the speed-responsive device.

Referring to Fig. 1, I have shown a steam turbine 5 and directly coupled to the revolving shaft thereof an alternating current generator 6, having slip rings! for conducting the exciting current from and external source of supply 8 to the field of the generator. A rheostat 9 is included in this field circuit for regulation of the exciting current. The alternator supplies current to electric motors 10, the revolving shafts of which are directly connected through propeller shafts 11 to propellers 12.

The turbine is provided with a compound admission valve comprising a series of valves 16, which are controlled by a cam shaft 17 and a hand-operated wheel 18, and which serve to admit elastic fluid, such for example, as steam, from the chest 19 through suitable nozzles or passages to the rotor of the turbine. The cams are arranged to open the valves in successive order and to similarly close them. Steam is admitted through the conduit or supply main 20 into the chest 19.

A speed-responsive device 21 is operatively connected to the revolving shaft of the -turbine in any well known manner. This devlce as shown in the drawings is of the centrifugal type and comprises the weights 22, as

spring 23 and rod 24. The rod 24 is connected to a lever arm 25,1 one end of which is 'fulcrumed at a point 26 on an extension of the casing of the device 21.

The other end of the lever 25 is connected to a rod 27 which is constructed in two parts flexibly connected by means of a sliding yoke 28 and the springs 29; The rod 27 is connected to one end of a floating lever 30,

pivoted at its middle point to the stem of the pilot valve 31 of a fluid pressure motor 32. The floating lever 30 is connected, by means of a link 33 and pivoted lever 34%, to the piston rod 35 of the fluid pressure motor.

The piston rod is provided with a rack 36 at its upper end which cooperates with a pinion 37 rigidly secured to the spindle of a throttle valve 38 located in thesupply main 20.

The operation of my novel and improved system is as follows :The speed responsive device is adjusted to operate the throttle valve only when the speed of the turbine reaches a certain predetermined maximum limit which is ordinarily slightly in excess of the maximum speed attained during the normal operation of the ship. When thespeed of the turbine is below this limit, the speed responsive device will in no way affect the operation ofthe turbine. the speed of the turbine exceeds this maximum value for which the speed responsive device is adjusted, the weights 22 will move outwardly and the pilot valve will be lowered through the cooperation of the lever 25, the rod 27 and the floating lever 30. Fluid under pressure is thereby admitted below the piston of the motor 32, and the piston rod 35 moves upwardly and tends too close the throttle valve 38. device comprising the lever 34 and link 33 is actuated by the piston rod and restores the pilot valve to its midposition, and the motor 32 comes to rest in its new position.

This operation will be repeated if necessary until the valve has been closed sufliciently to prevent the speed of the turbine exceeding the desired limit. The rod 27 is flexibly constructed in order to prevent objectionable strains on the mechanism in case the piston prevent, under these circumstances, the speed of the turbine rising above the predeter- When 95 The follow-up 105 driving 1 2 0 enerator 6, the turbinew'ill tend to spee up. The speed responsive device will avoided but one which also holds the generating unit in operation and at a speed in;

readiness for instant use when the electric circuits are reestablished. This greatly facilitates cha ges of electrical conditions 'for' reversal or c anges of speed, since it makes possible the interruption and reestablishment of the circuits without any attention being given to the prime mover, and at the same time does not interfere with the variation of the speed by controlof the steam admission at ranges below the predetermined speed .limit..

I the device is designed to operate.

Although I have shown as the speed. re sponsive device a standard centrifugal speed governor of ordinary construction, it is evident that I am using this device for a pur-- pose entirely different from that to which speed governors are ordinarily applied. In the normal uses of my improved system, this speed'responsive device will be entirely out of efl'ective action, the speeds under such conditions being-below the range atwhich i The'function of the device is to liinitthe speed oi the turbine at times when the electric load is re- Y moved, and tohold the turbine in readiness to again do its normal work when the electric load is reestablished. The speed responsive device thus limits'the turbine speed, in that it prevents the speed'of the turbine rising above a predetermined value. Whenthe turbine speed rises to this predetermined value, as for example, when the load is removed from the turbo-alternator speed responsive device acts in thenature of a governor with respect to this particular speed, ii that it maintains the turbine in an operative running condition at approximately this predetermined speed. Thetur- -'bine contmuesto run'without load at this predetermined speed, and under this condition the speed responsive device operates to maintain this predetermined speed of the turbine, but as soon as the load is again thrown on the turbo-alternator unit, theturbine speed falls to its normal opera mg speed as determined bytheposltlon of the hand operated valves 16,-but the speed responsive device now has no further action thanto hold open the valve 38. lWithout such a speed-responsive device as have to make all cha'n es oi shown, it is necessary electrical connec ions under load, or to capable unit, the

\ crating cut off the steam supply entirely and start the turbine afresh after making the change of connections. The'change of connections under load involves avariety of difiiculties, not only through the switching of large currents, but throu h the momentary interruption of load which allows the turbine to increase its speed. With the speed responsive devlce herein-described, changes of connections can-be made at no load and without stoppingthe turbine.

The system of turbine by means of the hand-operated valves. The speed responsive device is inof increasingthe quantity ofsteam admitted beyond the limits established by the hand-operated valves, but isfcapable of restricting'at any time, whenthe speed of propulsion which I have described is ideally simple with respect to the electrical arrangements, no electric means the turbine exceeds the predetermined limit,

the admission of steam. The governor therefore acts to establish the limit-of speed, and the hand-operated valves act tfnder'normal operating conditions to limit the quantity ofste'amadmission. U

In accordance with the provisions of the patent statutes, I have described the prin ci leof operation of. my invention, together with the a paratuswhich I now consider to ebest embodiment. thereof; but

represent t I desire to have it understood that the. apparatus shown isonly illustrative, and that the invention"canfbecarried outby other means.

ioo I What I claim asinew and-desire to" secure" byLetters Patent of theUnited States, is

A ship propulsionsystem compr sing in; 7

1. combination, an elastic fluid- ".turb1ne,;. an alternatoricoupled to saidgturbinef a'fpropeller driving motor. electrical to said alternator, and mean thesIISJeed of the shi spee v normally. en p py'ed in the navigatio of the shi by varymg stantpredetermined speed when the load is removed from the turbine.

to said lternator, andmeans for varying thespeed of the ship by varying the admission of elastic fluid to said turbine and for maintaining said turbine when the load is p the speedof said I bine and" or holding said: turbine inan o'pconditionatan approximately cons I 1 peller driving motor electrically connected.-

removed therefrom in an operative running condition at a speed slightly in excess of the maximum speed employed in the normal navigation of the ship.

3. A ship propulslon system comprising in combination, an elastic fluid turblne, an alternator coupled to said turbine, a propeller driving motor electrically connected to said alternator, a speed responsive device ada ted when the speed of the turbine slig tly exceeds the maximum operating speed normally employed in the navigation of the ship to maintain said turbine in an operating condition and to limit its s eed, and means independent of said spee re sponsive device for varying the speed of said turbine to vary the speed of the ship. 4. A ship propulsion system comprising in combination, an elastic fluid turblne, an alternator-coupled to said turbine, a propeller driving motor electrically connected to said alternator, a speed responsive device in operative relation to said turbine for maintaining a no-load speed of the turbine, and means independent of said speed responsive device for controlling the speed of said turbine for obtaining the speeds required in the normal navigation of the ship.

5. A ship propulsion system com rising in combination, an elastic fluid turbine, an alternator coupled to said turbine, a propeller driving motor electrically connected to said alternator, means for varying the speed of said turbine through the range necessary to obtain the desired speeds employed in the navigation of the ship and for maintaining said turbine in an operative running condition when the load is removed therefrom.

6. A ship propulsion system comprising in combination, an elastic fluid turbine, an alternator coupled to. said turbine, a propeller driving motor electrically connected to said alternator, means for controlling the admission of elastic fluid to said turbine to obtain the speeds required in the navigation of the ship, and a speed responsive device inactive during normal operating speeds of the turbine but adapted at no-load to main tain said turbine in an operative running condition and at a speed slightly in excess of its normal maximum operating speed.

/ 7. A ship propulsion system comprising in combination, an elastic fluid turbine, an

alternator coupled to said turbine, a pro- I.

peller driving motor electrically connected to said alternator, means for controllingthe amount of elastic fluid admitted to said tur bine to obtain the speeds required in the navigation of the ship, and a speed responsive device inactive during normal operating speeds of the turbine but adapted to act as a speed governor to approximately maintain a predetermined turbine speed when mamas the speed of the turbine attains such predetermined value. 7

8. A ship propulsion system comprising in combination, an elastic fluid turbine, an alternator coupled to said turbine, a propeller driving motor electrically connected to said alternator, a conduit for supplying elastic fluid to said turbine, manually operable means for varying the quantity of elastic fluid admitted to said turbine thereby varying the speed of the turbine and accordingly the speed of the propeller driving motor, a throttle valve in said conduit, and a speed responsive device operatively related to said turbine and cooperating with said throttle valve and adapted to limit the speed of the turbine when the turbine speed slightly exceeds the maximum operating in combination, an elastic fluid turbine, an

alternator coupled to said turbine, a propeller driving motor electrically connected to said alternator, means for adjusting the amount of elastic fluid admitted to said turbine to obtain the speeds required in the navigation of the ship and for maintaining said turbine in an operative running condition when the load of said propeller driving motor is removed from said alternator.

10. A ship propulsion system comprising in combination, an elastic fluid turbine, an alternator coupled to said turbine, a propeller driving motor electrically connected to said alternator, and means for controlling theamount of elastic fluid admitted to said turbine to vary the speed of the turbine for obtaining the turbine speeds required in the navigation of the ship and for maintaining an approximately constant turbine ,speed when the load of said propellerdriving motor is removed from said alternator.

' 11. A ship propulsion system comprising in combination an elastic fluid turbine, an alternator coupled to said turbine, a propeller driving motor electrically connected to said alternator, a conduit for supplying elastic fluid to said turbine, a throttle valve in said conduit, a speed responsive device 'for partially closing said throttle valve to said alternator, a valve for controllingthe admission of elastic fluid to said turbine, means for operating said valve, a conduit for supplying elastic fluid to said turbine, a valve normally inactive in said con.- duit, and a speed responsive device for operating said conduit valve and' for maintaining said turbine in an operating condition when the speed of the turbine attains a predetermined maximum value.

In witness whereof, I havehereunto set my hand this 16th day of September, 1912.

WILLIAM L., R. EMMET.

Witnesses:

' BENJAMIN B. HULL,

HELEN ORFORD. 

